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1 | .\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk |
2 | .\" <mtk.manpages@gmail.com> | |
3 | .\" | |
93015253 | 4 | .\" %%%LICENSE_START(VERBATIM) |
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5 | .\" Permission is granted to make and distribute verbatim copies of this |
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9 | .\" Permission is granted to copy and distribute modified versions of this | |
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11 | .\" entire resulting derived work is distributed under the terms of a | |
12 | .\" permission notice identical to this one. | |
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14 | .\" Since the Linux kernel and libraries are constantly changing, this | |
15 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
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18 | .\" have taken the same level of care in the production of this manual, | |
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20 | .\" professionally. | |
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22 | .\" Formatted or processed versions of this manual, if unaccompanied by | |
23 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 24 | .\" %%%LICENSE_END |
02afffe0 | 25 | .\" |
4b8c67d9 | 26 | .TH CLOCK_NANOSLEEP 2 2017-09-15 "Linux" "Linux Programmer's Manual" |
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27 | .SH NAME |
28 | clock_nanosleep \- high-resolution sleep with specifiable clock | |
29 | .SH SYNOPSIS | |
30 | .B #include <time.h> | |
31 | .nf | |
68e4db0a | 32 | .PP |
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33 | .BI "int clock_nanosleep(clockid_t " clock_id ", int " flags , |
34 | .BI " const struct timespec *" request , | |
35 | .BI " struct timespec *" remain ); | |
36 | .fi | |
68e4db0a | 37 | .PP |
02959991 | 38 | Link with \fI\-lrt\fP (only for glibc versions before 2.17). |
68e4db0a | 39 | .PP |
9a30939e | 40 | .ad l |
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41 | .in -4n |
42 | Feature Test Macro Requirements for glibc (see | |
43 | .BR feature_test_macros (7)): | |
44 | .in | |
68e4db0a | 45 | .PP |
02afffe0 | 46 | .BR clock_nanosleep (): |
9a30939e | 47 | .RS 4 |
a446ac0c | 48 | _POSIX_C_SOURCE\ >=\ 200112L |
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49 | .RE |
50 | .ad | |
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51 | .SH DESCRIPTION |
52 | Like | |
53 | .BR nanosleep (2), | |
54 | .BR clock_nanosleep () | |
2b1c23bd | 55 | allows the calling thread to sleep for an interval specified |
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56 | with nanosecond precision. |
57 | It differs in allowing the caller to select the clock against | |
58 | which the sleep interval is to be measured, | |
59 | and in allowing the sleep interval to be specified as | |
60 | either an absolute or a relative value. | |
efeece04 | 61 | .PP |
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62 | The time values passed to and returned by this call are specified using |
63 | .I timespec | |
64 | structures, defined as follows: | |
0ffeaeae | 65 | .PP |
02afffe0 | 66 | .in +4n |
0ffeaeae | 67 | .EX |
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68 | struct timespec { |
69 | time_t tv_sec; /* seconds */ | |
70 | long tv_nsec; /* nanoseconds [0 .. 999999999] */ | |
71 | }; | |
0ffeaeae | 72 | .EE |
02afffe0 | 73 | .in |
efeece04 | 74 | .PP |
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75 | The |
76 | .I clock_id | |
77 | argument specifies the clock against which the sleep interval | |
78 | is to be measured. | |
79 | This argument can have one of the following values: | |
80 | .TP 17 | |
81 | .BR CLOCK_REALTIME | |
82 | A settable system-wide real-time clock. | |
83 | .TP | |
84 | .BR CLOCK_MONOTONIC | |
24b74457 | 85 | A nonsettable, monotonically increasing clock that measures time |
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86 | since some unspecified point in the past that does not change after |
87 | system startup. | |
88 | .\" On Linux this clock measures time since boot. | |
89 | .TP | |
90 | .BR CLOCK_PROCESS_CPUTIME_ID | |
91 | A settable per-process clock that measures CPU time consumed | |
92 | by all threads in the process. | |
93 | .\" There is some trickery between glibc and the kernel | |
94 | .\" to deal with the CLOCK_PROCESS_CPUTIME_ID case. | |
95 | .PP | |
96 | See | |
0eb44391 | 97 | .BR clock_getres (2) |
02afffe0 | 98 | for further details on these clocks. |
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99 | In addition, the CPU clock IDs returned by |
100 | .BR clock_getcpuclockid (3) | |
101 | and | |
102 | .BR pthread_getcpuclockid (3) | |
103 | can also be passed in | |
104 | .IR clock_id . | |
efeece04 | 105 | .PP |
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106 | If |
107 | .I flags | |
108 | is 0, then the value specified in | |
109 | .I request | |
110 | is interpreted as an interval relative to the current | |
111 | value of the clock specified by | |
112 | .IR clock_id . | |
efeece04 | 113 | .PP |
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114 | If |
115 | .I flags | |
116 | is | |
117 | .BR TIMER_ABSTIME , | |
118 | then | |
119 | .I request | |
120 | is interpreted as an absolute time as measured by the clock, | |
121 | .IR clock_id . | |
122 | If | |
123 | .I request | |
124 | is less than or equal to the current value of the clock, | |
125 | then | |
126 | .BR clock_nanosleep () | |
127 | returns immediately without suspending the calling thread. | |
efeece04 | 128 | .PP |
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129 | .BR clock_nanosleep () |
130 | suspends the execution of the calling thread | |
131 | until either at least the time specified by | |
132 | .IR request | |
133 | has elapsed, | |
134 | or a signal is delivered that causes a signal handler to be called or | |
135 | that terminates the process. | |
efeece04 | 136 | .PP |
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137 | If the call is interrupted by a signal handler, |
138 | .BR clock_nanosleep () | |
81a0028c | 139 | fails with the error |
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140 | .BR EINTR . |
141 | In addition, if | |
142 | .I remain | |
143 | is not NULL, and | |
144 | .I flags | |
145 | was not | |
146 | .BR TIMER_ABSTIME , | |
147 | it returns the remaining unslept time in | |
148 | .IR remain . | |
149 | This value can then be used to call | |
150 | .BR clock_nanosleep () | |
151 | again and complete a (relative) sleep. | |
47297adb | 152 | .SH RETURN VALUE |
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153 | On successfully sleeping for the requested interval, |
154 | .BR clock_nanosleep () | |
155 | returns 0. | |
156 | If the call is interrupted by a signal handler or encounters an error, | |
535f0df5 | 157 | then it returns one of the positive error number listed in ERRORS. |
02afffe0 | 158 | .SH ERRORS |